Automotive pressure carburetor



May 13, 1952 w; JR 2,596,429

AUTOMOTIVE PRESSURE CARBURETOR Filed Aug. 8, 1946 441M Orzwiz:

INVENTOR. W

,H TTORNFY Patented May 13, 1952 AUTOMOTIVE PRESSURE CARBURETOR AndrewWilliam Orr, J r., Detroit, Mich., assignor to George M. Holley and EarlHolley Application August 8, 1946, Serial No. 689,260

The object of this invention is to incorporate in a small aircraft or inan automotive type carburetor the well known features of the largeaircraft carburetors now in general use.

Specifically, the object is to modify these well known features andadapt them for use on vehicles such as trucks and for smaller airplaneengines.

The figure shows the preferred form of my invention.

In the drawing [8 is the air entrance, [2 is the venturi, I4 is thethrottle, I6 is the mixture outlet into which the fuel nozzle 18discharges. The control of the fiow through this nozzle is the subjectof this invention.

2 Claims. (01. 261-51) 28 is a link connecting the throttle [4 with a acam 24. A link 22 is the manual throttle control. The cam 24 engageswith a piston 28 which engages with a spring 28 which engages with adiaphragm 38. Increased pressure is applied to the diaphragm 38 when thethrottle I4 is almost closed. 32 is a passage through which the pressurein the air entrance I0 is applied to the upper surface of the diaphragm30 which responds to 'air fiow by reason of 34 which is an openingthrough which the suction in the throat of the venturi I2 is applied tothe lower surface of the diaphragm 38.

A fuel control element 36 is engaged by the airflow responsive diaphragm38 and is engaged by the diaphragm 38 responsive to fuel flow. Fuelenters below the diaphragm 38 from an entrance 48. An element 31 engageswith the element 38 and controls the flow past a valve seat 54.

A needle valve 42 connected through a lever 44 with the throttle [4provides the low speed fuel control means. When the throttle I4 isopened any appreciable amount the needle 42 is withdrawn entirely andoffers no resistance whatever to the flow of fuel. The resistance thento the flow is that offered by the restriction 48 without the needle 42.

Normally the fuel flows through the restriction 48, through the valveseat 54, past the needle 58 (which when the engine in not running isseated by the compression spring 58), and so to the fuel nozzle l8. Adiaphragm 51 is connected to the needle valve 56 to support the spring58.

Economizer The restriction 18 is effective and enrichens the mixture atwide open throttle (low suction) when the spring 88 opens the valve 68.

Acceleration A piston 10 engages with a spring 12 and dis charges fuelfrom the chamber 82 past the valve 56 into the nozzle I 8. When thethrottle is closed the check valve 84 admits fuel freely to the chamber82.

Priming In order to get a rich mixture to start, a lever 88 engages witha piston 88 and the piston 88 engages with a spring 88, which spring 98is seated on the diaphragm 38. When the lever 86 is rotatedanti-clockwise the spring 98 is compressed and the valve 36 is depressedso that the fuel freely passes the valve seat 54.

A fuel pump of a well known type 92 driven preferably by an electricmotor 94, which receives its energy from a storage battery 96 isprovided.

Operation When idling the pressure on the diaphragm 38 is increased bythe cam 24 engaging with the spring 28. The fuel thus flows past theneedle valve 42 which restricts the restriction 48. The fuel flowthrough 40-42 creates a pressure drop equal to the spring pressure 28plus that due to the air diaphragm 38.

As the throttle is opened the needle valve 42 is withdrawn and the cam24 is rotated so that the load on the spring 28 is removed. The flow ofair and fuel then follows a fixed ratio, as the air flow, acting on thediaphragm 38, balances the diaphragm 38 acted on by the drop in pressureof the fuel flowing past the restriction 48. At high manifold pressure(absolute) the restriction 48 is supplemented by the restriction 18which is in parallel with the restriction 48.

The low speed fuel operation follows an empirical regulation determinedby the taper of the needle 42 and the shape of the cam 24. The automaticcontrol follows the removal of the empirical control means.

The priming and warm-up system 86-88-98 has the advantage of providing aricher mixture at wide open throttle where the manifold pressure(absolute) is higher and hence the evaporation is lower than at partthrottle when the manifold pressure (absolute) is lower and hence theevaporation greater.

What I claim is:

1. In a pressure type carburetor a source of fuel under pressure, a fuelentrance leadin therefrom, a diaphragm responsive to the pressure of theentering fuel, a fuel passage, a fuel restriction therein admitting fuelto the other side of said diaphragm, a fuel outlet leading from the lowpressure side of said diaphragm, a valve in said outlet adapted to openagainst the fuel flow therethrough, said diaphragm being con:nctedtosaidvalve, an air entrance, a venturi therein; a diaphragmresponsive to the. airflow and connected to said fuel valve so as tomove in opposition to said first diaphragm, a throttle in the airoutlet, yieldable means connected to said throttle imposing a load onsaid airdiaphragm source of fuel under pressure, a fuel entrance leadingtherefromka fueldiaphragm responsive to the pressure of "the enteringfuel, a fuel passage, a fuel restriction therein admitting fuel-to theother side of said fuel diaphragm, a fuel outlet leading'from the, lowpressure. side vof said fuel diaphragm, avalve therein; adapted to beopened :by said' fuel ,r diaphragmaas. it moves. in

response to the pressure drop at said restriction,

, an air entrance, a venturi therein, an air diaphragm responsive to thedepression in the throat of said venturi and connected to said fuelvalve so as to move it in opposition to the movement imposed on saidvalve by said fuel diaphragm, an air outlet, a throttle in said airoutlet, yield- ,able meansnassociated with .said air diaphragm andresponsive only to the closing movement of said throttle for imposing anadditional load on said air diaphragm only when the throttle is almostclosed, a needle valve connected to said .air throttleand, adapted toenter said fuel restriction only when said air throttle approaches '15'its closed. position.

ANDREW WILLIAM ORR, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

v UNITED' STATES PATENTS Number ame Date 2,372,306 :Adair 'Mar. 27, 194525 2,390,658 :Mock Dec. 11, 1945 2,392,055 Mennesson Jan. 1, 1946

